Bicycle carrier bags are widely used by recreational bicyclists to carry with them when they ride articles of all descriptions, perhaps the most common articles being tools, food, beverages, and clothing. Bicycle carrier bags include handlebar bags, seat bags, and front and rear rack panniers.
It has long been common for manufacturers of bicycle carrier bags to equip them with light reflectors to enable motorists to see the bicycle at night. Ordinarily, there will be a single reflector In the case of bags visible from the rear, a red reflector facing rearwardly is often provided. Many bags that are visible from the front have white reflectors that face forwardly. The effectiveness of reflectors on carrier bags in making the presence of a bicycle known to motorists varies considerably with many factors, such as the location and orientation of the bicycle relative to the motorist, the distance between the bicycle and the motorist, and the setting of the vehicle headlights (high or low beam). Reflectors facing to the front or rear, as the case may be, are visible through only a relatively small angle near the longitudinal axis of the bike, so a reflector on a carrier bag of a bicycle moving around a curve, for example, will not be seen until a motorist is very close. Similarly, a vehicle with its headlights on low beam will not illuminate the reflectors at large distances. It is also common for some carrier bags to be deformed by the load they are carrying, so they do not face in a direction that is optimal to reflecting light back to a remote observer.